The present invention generally relates to earthworking equipment and, in a preferred embodiment thereof, more particularly relates to quick coupler apparatus for releasably attaching excavator buckets and other implements to heavy construction equipment such as a hydraulic excavator.
In the excavation and earthworking industry various types of quick coupler devices have previously been utilized to provide for rapid connection and removal of various work implements, such as buckets, blades, claws and the like, to the articulated boom portion of a prime mover such as, for example, a hydraulic excavator. Typically, a quick coupler has a body portion with top side stick and curl pins to which lift and curl arm outer end portions of the boom are connected, and bottom side portion recesses which removably receive stick and curl pin portions of the implement to be connected to the boom via the quick coupler. A locking mechanism is incorporated in the quick coupler and is operative to releasably hold the implement stick and curl pins within the quick coupler recesses.
As the name implies, the primary advantage of the typical quick coupler is the speed with which it permits a selected implement to be connected to the prime mover boom. Before the advent of quick coupler devices of this sort, a selected work implement had to be connected directly to the outer boom end by driving the boom stick and curl pins through aligned holes in the implement and boom linkage portions. subsequent removal of the implement from the boom required that the stick and curl pins be driven out of the implement and boom linkage portions.
Although the now common use of this type of coupler device to interchangeably connect various work implements to prime mover booms by simply latching bottom side portions of the coupler to the stick and curl pin portions of the implement has markedly simplified and quickened the implement attachment process, conventional quick couplers of this general type carry with them various types of well known problems, limitations and disadvantages.
For example, as a conventional quick coupler and the implement pins to which it is removably attached begin to wear, the overall coupler/implement pin interface begins to loosen, thereby tending to cause undesirable xe2x80x9cchatterxe2x80x9d between the coupler and the implement. While some previously utilized couplers have a limited amount of adjustment to compensate for wear and differences in implement pin-to-pin centerline spacing, it is often difficult to achieve tight coupler-to-implement pin contact when such centerline distance drifts outside of a predetermined, rather limited range, to prevent this chatter
Additionally, it is quite important to assure that the heavy equipment implement does not come loose from the quick coupler unless and until the equipment operator intends it to do so. Despite the importance of this design aspect from a safety standpoint, various conventional quick coupler designs have proven to be less than optimal from this design standpoint.
Another problem often associated with quick couplers of conventional design is that with respect to at least one of the implement pins to which the coupler is releasably latched the contact area between the coupler and the pin is relatively small. This concentrates the typically quite high coupler load on such pin along a relatively small area of the pin. In turn, this concentrated load on a relatively small area of the pin hastens pin wear and more quickly loosens the fit between the coupler and the implement pins to which it releasably attaches.
As can be readily seen from the foregoing, a need exists for a quick coupler which eliminates or at least substantially reduces the above-mentioned problems, limitations and disadvantages typically associated with quick couplers of conventional construction. It is to this need that the present invention is directed.
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, a specially designed quick coupler apparatus is provided for releasably attaching a work implement having spaced apart first and second attachment pins, representatively an excavation bucket, to a boom of a prime mover such as the vehicular portion of an excavator.
The quick coupler apparatus representatively comprises a body portion releasably securable to the boom and having spaced apart first and second recess areas operative to respectively and releasably receive the first and second work implement attachment pins. A latch member is carried by the body portion for movement relative thereto between (1) a locking position in which the latch member engages a first side portion of the received first attachment pin in a manner captively retaining the received first and second attachment pins respectively in the first and second recess areas, and (2) an unlocking position in which the latch member is disengaged from the first attachment pin and permits removal of the first and second attachment pins respectively from the first and second recess areas.
Preferably, the latch member has a generally hook-shaped configuration and is translatable between its locking and unlocking positions. In its locking position the latch member complementarily engages the received first attachment pin around a generally semicircular circumferential portion thereof. A drive structure, illustratively a pilot pressure-operable hydraulic cylinder assembly, is provided and is operative to selectively translate the latch member between its locking and unlocking positions.
In a preferred embodiment thereof the quick coupler apparatus has incorporated therein a redundant safety system that serves to prevent unintentional unlocking of the latch member. The redundant safety system illustratively includes (1) a check valve portion of the hydraulic cylinder assembly operative, in response to a loss of hydraulic pressure to the valve when the latch member is in its locking position, to hydraulically lock the latch member in its locking position, (2) a spring structure resiliently biasing the latch member toward its locking position, and (3) a blocking member extendable through aligned openings in the quick coupler body portion, when the latch member is in its locking position, and operative to mechanically block the latch member against movement from its locking position to its unlocking position.
As an additional safety feature, the spring structure is carried on an elongated guide rod which, when the latch member is translated to its unlocking position, longitudinally extends outwardly through an opening in an exterior wall of the body portion to give the equipment operator or other observer a visual indication that the latch member is in its unlocking position.
According to another aspect of the invention, a stop structure is provided and is operative to engage the received first attachment pin on a second side portion thereof, preferably opposite from the first side portion of the pin engageable by the latch member. The stop structure, in its preferred embodiment includes a stop member which is adjustably translatable toward and away from the latch member to thereby contact the received first attachment pin and dimensionally compensate for different implement pin-to-pin spacings and/or wear at the coupler/implement interface area.
The stop member preferably has an arcuate surface area complementarily engageable with a side portion of the received first attachment pin, and is secured to the body portion for translational movement toward and away from a surface thereof. The stop structure, in its preferred embodiment, further includes a selectively variable number of shim members releasably supported between the stop member and the surface of the body portion. By simply varying the number of shims interposed between the stop member and the body portion surface, the distance between the stop member and the second recess area can be easily and selectively varied.